chore: upgrade react-router from 5.0.1 to 5.1.0

Snyk has created this PR to upgrade react-router from 5.0.1 to 5.1.0.

See this package in NPM:
https://www.npmjs.com/package/react-router

See this project in Snyk:
https://app.snyk.io/org/xmartinezpujol/project/9e43f135-1ef6-4d26-969f-83e85ec0e7cf?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -9,7 +9,7 @@
     "react-dom": "^16.9.0",
     "react-markdown": "^4.2.2",
     "react-redux": "^7.1.1",
-    "react-router": "^5.0.0",
+    "react-router": "^5.1.0",
     "react-router-dom": "^5.0.0",
     "react-syntax-highlighter": "^11.0.2",
     "redux": "^4.0.4",